JPS6173112A - Tape-shaped optical fiber unit - Google Patents

Abstract

PURPOSE:To suppress microbends occurring in optical fiber elements at low temp. to the lower limit by specifying relationships among the outside diameters of the optical fiber elements and their number, and the thickness and width of the tape-shaped unit. CONSTITUTION:The tape-shaped optical fiber unit 5 provided with a cover layer 2 and a protective layer 4 not adhering to each other is controlled so as to have relationships: 1.1<=T/d<=1.45 and 1.0<W/nd<=1.08, where d and n are the outside diameter and the number of the optical fiber 1 elements 3 forming the optical fiber unit 5 respectively, T is the outside diameters of the elements 3, T is the thickness of the unit 5, and W is its width. As a result, even when the unit 5 is exposed to low temp., occurrence of stress due to the contraction of the resin is very small, and microbends occurring in the element 3 can be suppressed to an extent as small as causing only a minute amt. of transmission loss of the elements 3, thus permitting the elements 3 to be prevented from breakdown to pieces, and the obtained tape-shaped optical unit 5 to be thinned and improved in junction operation efficiency.

Description

Detailed Description of the Invention [Technical Field] The present invention provides an optical fiber assembly in which a plurality of optical fibers each having a coating layer made of an ultraviolet curable resin are arranged in parallel in a plane. The present invention relates to a tape-type optical unit in which a protective layer made of a curable resin is integrally provided on the optical fiber assembly.

[Prior art]

In anticipation of the construction of future optical fiber subscriber lines, various optical fiber cables are being prototyped and various studies are being conducted today. By the way, when constructing an optical fiber subscriber line, what is required of an optical fiber cable is not only long-term double-n property (but also the ability to accommodate more optical fibers in a cable of the same outer diameter). What you can do,
The second is that it can be supplied at a lower price. In order to satisfy these required characteristics, several cables or units for use with the cables have been devised and studied. As a representative example,
For example, there is a tape type optical unit 5 shown in FIG. In this method, a plurality of optical fibers 3 each having a coating layer 2 made of an ultraviolet curable resin arranged around the optical fiber 1 are arranged in parallel in a plane to form an optical fiber assembly. A protective layer 4 made of ultraviolet curable resin is integrally provided. When a plurality of tape-type optical fiber units 5 are stacked to form a cable, the tape-type optical unit 5 constructed in this way can accommodate more optical fibers within a cable of the same outer diameter than a conventional round-shaped optical fiber unit 7 that is assembled with a plurality of pieces. It has the feature of being able to accommodate the strands 3. Moreover, coating N2
Since both the S1 layer and the protective S1 layer 4 are made of an ultraviolet curable resin having a fast curing speed, it is possible to increase the manufacturing line speed and thereby reduce the manufacturing cost. However, despite having such excellent characteristics, the tape-type optical unit 5 is prone to microhend when exposed to low temperatures or subjected to external force, and as a result, the optical fiber There is a drawback that transmission loss of the wire 3 increases. The reason for this is that the coating layer 2 and the protective layer 4 are bonded together, so when the protective layer 7114 contracts at low temperatures, the coating layer 2 of the optical fiber 3 is pulled by the shrinking protective layer 4. ,the result,
Distortion occurs here and there in the longitudinal direction of the tape-type optical unit 7, causing microhends in the optical fiber strand 3. That is, it is presumed that this is because the stress accompanying the shrinkage of the protective i1 layer 4 remains between the optical fiber strand 3 and the protective i1 layer 4 without being relieved. Therefore, efforts have been made to eliminate the adhesion between the coating layer 2 and the protective layer 4 of the optical fiber strand 3 and to relieve the stress remaining between the two layers by sliding between the two layers. However, in this way, the optical fiber
If the structure prevents adhesion between A3 and the retainer 11114, it will be as if a plurality of optical fins < strands 3 are restrained by the tape-like retainer 1114. When the protective layer 4 becomes thin, the binding force of the optical fiber 3 by the protective layer 4 becomes insufficient, and small external forces, such as dirt when winding this tape-type optical unit 5 around a drum, become larger. Looking at the tape-shaped optical unit 5 wound around the drum, even if only the tension of
The protective layer 4 may be torn and the optical fibers 3 may become separated. Conversely, if the protective layer 4 is thick (as described above, when this tape-type optical unit 5 is exposed to low temperatures, the shrinkage force of the protective layer 4 will increase, causing microhends in the optical fiber 3). It is easy to do.

Alternatively, due to the contraction force, the black (
There is also the problem that the arrangement of the optical fibers 3 is distorted, and as a result, the connection workability of the tape-type optical unit 5 is deteriorated. Also, of course, Tamotsu:! If F14 becomes thicker, the thickness of the tape-type optical unit 5 also increases, and when it is made into a cable, there is a problem that the storage rate of the tape-type optical unit 5 decreases.

[Purpose of the invention]

To solve the above problem, the object of the present invention is to solve the problem even when exposed to low temperatures.
To provide a thin tape-type optical unit that minimizes microhends occurring in optical fiber cotton and does not cause alignment distortion even when an external force normally applied to a cable is applied.

[Structure of the invention]

In order to achieve the above object, the tape-type optical unit of the present invention has an optical fiber assembly in which a plurality of optical fiber asbestos having a coating layer made of an ultraviolet curable resin are arranged in parallel in a plane, and an ultraviolet curable resin is integrated into the optical fiber assembly. A tape type optical unit provided with a protective layer made of resin, the coating layer and the protective layer =5.
In a tape-type optical unit in which the layers are not in contact with each other, the outer diameter of the optical fiber is d, the number of optical fibers forming the optical fiber assembly is n, and the thickness of the tape-type optical unit is When T is the width and W is the width, 1.1≦T/d
≦1.45.1.0 <W/nd≦1.08.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the tape-type optical unit 5 of the present invention has a plurality of optical fibers 3 arranged in parallel in a plane, each having a coating layer 2 made of an ultraviolet curable resin around an optical fiber l. In a tape type optical unit 5 in which a protective layer 4 made of an ultraviolet curable resin is integrally provided on an optical fiber assembly with a cover plate that does not adhere to the VL cover layer 2, the outer diameter of the optical fiber strand 3 is d, where n is the number of optical fiber strands 3 forming the optical fiber assembly, T is the thickness of the tape-type optical unit 5, and W is the width, 1.1≦T/
It is characterized in that d≦1.45.1.0<W/nd≦1.08. Here, the case where there is a plurality of layers made of ultraviolet curable resin as the coating layer 2 is also included.

If the shape of the tape-type optical unit 5 is restricted as described above, the increase in transmission loss of the optical fiber 3 at low temperatures will be very small, and the S1 layer 4 will not be torn or the optical fiber 3 will be damaged.
This eliminates the problem of the array being distorted. Here, the basis for determining these conditions will be explained with reference to FIGS. 3 and 4. In addition, in these figures, the reciprocal of the tension that separates is taken on one vertical axis, but the tension that separates here is
This refers to the tension that occurs when each optical fiber strand 3 of the tape-type optical unit 5 is separated into pieces due to the winding tension when the tape-type optical unit 5 shown in FIG. 1 is wound around a drum. Therefore, when taking its reciprocal, a larger value means that each optical fiber strand 3 comes apart with a smaller tension. First, explanation will be given starting from FIG. In Fig. 3, the horizontal axis shows T/d, and the vertical axis shows the increase in transmission IM loss (dB/km) of the optical fiber cotton 3 at -40°C and the reciprocal of the above-mentioned separating tension (1/kg). ), and the curve MA shows the change in the increase in transmission loss of the optical fiber 3 at -40°C, and the curve B shows the change in the reciprocal of the separating tension.

As can be seen from this figure, the limit of the increase in transmission loss of the optical fiber 3 at -40'C is 0.2 (d8/k+a
) Hereinafter, we will apply conditions that are very generally required for the optical fiber cotton 3 and the tape type optical unit 5, such as the limit of the reciprocal of the separation tension to be 5 (1/kg) or less, that is, 0.2 kg or more. The area that satisfies these conditions is the shaded area in the figure. That is, 1.1≦T/d≦1.
It can be seen that 45 is sufficient. Furthermore, in Figure 4,
The horizontal axis shows -/nd, the vertical axis shows the increase in transmission loss (dB/km) of the optical fiber 3 at -40°C and the reciprocal of the above-mentioned separating tension (1/kg), and ,
Similarly to FIG. 3, the curve A shows the change in the heating increase in the transmission of the optical fiber 3 at -40° C., and the curve B shows the change in the reciprocal of the separating tension. As can be seen from this figure, the limit of the increase in transmission loss of the optical fiber 3 at -40°C is 0.2 (ds/km) or less, and the upper limit of the reciprocal of the separating tension is 5 (1/+r ) or less, i.e. 0.2 kg
As mentioned above, as in the case of FIG. 3, if we apply the conditions that are very generally required for the optical fiber 3 and the tape-type optical unit 5, the area that satisfies these conditions is the shaded area in the figure. Become. In other words, 1.0 < W/
It can be seen that it is sufficient if nd≦1.08. As described above, in the tape type optical unit in which the coating layer 2 and the protective layer 4 are provided in a non-adhered state as in the present invention, the outer diameter of the optical fiber strand 3 is d, and the optical fiber assembly is formed. When the number of optical fiber elements VA3 to be used is n, the thickness of the tape-type optical unit 5 is T, and the width is W, 1.1 ≦T.
/d≦1.45.1.0 <W/d≦1.08, even if this tape-type optical unit 5 is exposed to low temperatures, stress due to resin contraction will be minimal, and the optical The microhend generated in the optical fiber 3 also increases the amount of transmission loss increase of the optical fiber 3 by at most 0.2 (dB/
km) Just push it up. In addition, the tension exerted by each optical fiber strand 3 of the tape type optical unit 5 is also 0.2
kg or more, the optical fiber cotton 3 will not come apart in the range of normal use, so there will be no problems with connection work, etc. Of course, the thickness of the tape type optical unit 5 is determined as described above. Since it suppresses scratching force in terms of both low-temperature properties and connection workability, there is no need to worry about increasing the outer diameter of the cable when it is made into a cable.

〔Effect of the invention〕

As described above (according to the present invention), even when exposed to low temperatures, the amount of increase in heating of the optical fiber transmission is negligible, and moreover, the external force applied to each optical fiber under normal use is It is possible to obtain a thin tape-type optical unit that does not come apart and has good connection workability.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a tape-type optical unit according to the present invention, FIG. 2 is a cross-sectional view of a tape-type optical unit showing a state of misalignment in a conventional tape-type optical unit, and FIG. 3 is a T/d A graph showing the relationship between -/nd and the transmission tH loss increase boundary under low temperature of the tape type optical unit and the reciprocal of the separating tension. FIG. 1--One optical fiber 2-M-Coating [13-Optical fiber cotton 4--One protective layer 5-Tape type optical unit (& η) L6 Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] This is a tape-type optical unit consisting of an optical fiber assembly in which a plurality of optical fibers each having a coating layer made of an ultraviolet curable resin are arranged in parallel in a plane, and a protective layer made of an ultraviolet curable resin is integrally provided thereon. In the tape type optical unit in which the coating layer and the protective layer are not bonded, the outer diameter of the optical fiber is d, the number of optical fibers forming the optical fiber assembly is n, and the When the thickness of the tape type optical unit is T and the width is W, 1.1≦T/d≦1
．． 45, tape-type optical unit characterized in that 1.0<W/nd≦1.08.